<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=375">
    <title>Document</title>
    <style>
        *{
            margin:0;
            padding:0;
        }
        #banner{
            width: 335px;
            height: 143.5px;
            background: #aef;
            margin: 97px auto 0;
        }
        .nav{
            width:335px;
            margin: 31px auto 0;
        }
        .item{
            width: 50px;
            height: 50px;
            background: #569;

        }
    </style>
</head>
<body>
    <div id="banner"></div>

    <div class="nav">
        <div class="item"></div>
    </div>
</body>
</html>